REMOBILIZATION OF 137CS FROM DEGRADATION OF PLANT BIOMASS IN SOILS
This investigation was focused on the role of humic acid-like compounds during the biodegradation of plant mass contaminated with 137Cs. The experiments were set up to distinguish cases of external and internal contamination. The results showed that 137Cs was associated with humic acid-like compounds in eluates from biomass and especially with their lighter fraction. The 137Cs in detritus was markedly mobile and only minor amounts were retained in biomass. These two variants differed in the rate of 137Cs release: while in the internally contaminated biomass the rate decreased during composting, in the externally contaminated biomass the rate increased. The radionuclide was carried by humic acid-like compounds, especially by these with relatively low molecular size. The good practice would be not to leave contaminated biomass on fields if soil is to be protected. From another point of view, the activity of 137Cs in collected biomass decreases in a few months on an acceptable level if this biomass is composted under controlled conditions.